In general, a junction box is used for concentrating electrical parts such as fuses, relays and the like in a motor vehicle.
As shown in FIG. 1, the junction box includes a main body 10 in which a plurality of electrical parts E is installed, an upper cover 20 configured to cover an upper portion of the main body 10, a lower cover 30 configured to cover a lower portion of the main body 10, sockets 12 installed on a lower surface of the main body 10 so as to be connected to the electrical parts E, and connectors 32 installed in the lower cover 30 so as to be coupled to the sockets 12.
The junction box further includes a plurality of fastening bolts 40 installed in the main body 10 and a plurality of fastening nuts (not shown) installed in the respective connectors 32 so as to be threadedly coupled to the fastening bolts 40.
The fastening bolts 40 are installed in the main body 10 so as to extend toward the respective connectors 32 of the lower cover 30. The fastening bolts 40 thus installed are threadedly coupled to the fastening nuts of the connectors 32.
When the fastening bolts 40 are rotated in a forward direction, the fastening nuts threadedly coupled to the fastening bolts 40 are moved upward along the fastening bolts 40 while making a screw motion, whereby the connectors 32 are moved upward together with the fastening nuts. Thus, the respective connectors 32 of the lower cover 30 are coupled to the sockets 12 of the main body 10.
When the fastening bolts 40 are rotated in a reverse direction, the fastening nuts are moved downward along the fastening bolts 40 while making a screw motion, whereby the connectors 32 are moved downward together with the fastening nuts. Thus, the respective connectors 32 of the lower cover 30 are separated from the sockets 12 of the main body 10.
As a result, in response to the operation conducted by a worker, the fastening bolts 40 and the fastening nuts serve to raise or lower the connectors 32 of the lower cover 30 so that the connectors 32 are coupled to or separated from the sockets 12.
However, in the conventional junction box mentioned above, the bolting structures of the fastening bolts 40 and the fastening nuts for coupling or separating the connectors 32 and the sockets 12 are installed for each of the connectors 32. The conventional junction box has a drawback in that the structure thereof is complex and a large number of parts are required. This leads to a problem that the manufacturing cost increases.
Furthermore, since the bolting structures of the fastening bolts 40 and the fastening nuts are installed for each of the connectors 32, the respective fastening bolts 40 needs to be individually operated one by one in order to couple or separate the connectors 32 and the sockets 12. For this reason, there is posed a problem in that the work of coupling and separating the connectors 32 and the sockets 12 is very onerous and time-consuming.
Moreover, since the bolting structures of the fastening bolts 40 and the fastening nuts are installed for each of the connectors 32, it is necessary to provide additional installation spaces in the connectors 32 and the main body 10. This poses a problem in that a loss of spaces occurs.
In particular, in the case of the main body 10 and the connectors 32, the space for installation of terminals and electrical parts is narrowed due to the bolting structures of the fastening bolts 40 and the fastening nuts. This poses a problem in that the configuration and arrangement of electrical parts are accompanied by a lot of restrictions.
In addition, the conventional junction box has a drawback in that during the course of raising and lowering the connectors 32 with the bolting structure, variations are generated in the raising and lowering amounts of the respective connectors 32.
Particularly, the raising and lowering amounts in the portions located away from the bolting structures are smaller than the raising and lowering amounts in the portions located close to the bolting structures. Such variations in the raising and lowering amounts in the respective portions may significantly reduce the ease of coupling of the connectors 32 with respect to the sockets 12. This poses a problem in that the sockets 12 and the connectors 32 may not be coupled to each other or may be coupled in a poor state.
In addition, the conventional junction box has a structure in which the connectors 32 are coupled to or separated from the sockets 12 of the main body 10 while moving upward or downward. Therefore, the length of wire harnesses 32a connected to the connectors 32 needs to be designed in view of the vertical movement stroke of the connectors 32.
Inasmuch as the length of the wire harnesses 32a has to be designed in conformity with the vertical movement stroke of the connectors 32, there is posed a problem that the manufacturing cost increases.
In order to solve the problems mentioned above, a one-bolt type junction box is disclosed in Korean Patent Application Publication No. 2015-173815.
As shown in FIGS. 2 and 3, the one-bolt type junction box disclosed in Korean Patent Application Publication No. 2015-173815 includes a main body 10 in which electrical parts E are installed, an upper cover 20 configured to cover an upper portion of the main body 10, a lower cover 30 configured to cover a lower portion of the main body 10, one or more sockets 12 installed on a lower surface of the main body 10, and one or more connectors 32 installed in the lower cover 30 so as to be coupled to the sockets 12. In the junction box, a single fixing bolt 60 is installed in the main body 10, and a single fixing nut 70 capable of being threadedly coupled to the fixing bolt 60 is installed in the lower cover 30. The main body 10 is moved upward or downward with respect to the connectors 32 through the use of the bolting structure of the fixing bolt 60 and the fixing nut 70. By conducting a bolting operation only once, it is possible to cause the sockets 12 of the main body 10 to be moved upward or downward with respect to the connectors 32 of the lower cover 30 so that the sockets 12 can be coupled to or separated from the connectors 32.
The one-bolt type junction box cited above further includes a guide means 80 for guiding the up/down movement of the main body 10 with respect to the connectors 32 of the lower cover 30.
The guide means 80 includes a plurality of guide rods 84 extending from the main body 10 toward the lower cover 30, and a plurality of guide tubes 82 configured to accommodate the guide rods 84 vertically moved together with the main body 10 and installed in the lower cover 30 so as to guide the up/down movement of the guide rods 84.
In the one-bolt type junction box cited above, the connectors 32 and the sockets 12 can be coupled and separated through the use of one bolt. It is therefore very easy and convenient to couple and separate the connectors 32 and the sockets 12. It is also possible to reduce the number of parts as far as possible and to save the manufacturing cost.
Moreover, in the one-bolt type junction box cited above, the connectors 32 and the sockets 12 can be coupled and separated even in a narrow space. Thus, the one-bolt type junction box is superior in maintainability and is capable of preventing poor connection between the sockets 12 and the connectors 32.
Since the connectors 32 and the sockets 12 can be coupled and separated through the use of one bolt, it is possible to prevent wear of parts which may occur at the time of coupling and separating the connectors 32 and the sockets 12. It is also possible to prevent reduction of the assembling accuracy.
However, as a result of actually applying and using the one-bolt type junction box cited above, the following drawbacks were found.
First, in the one-bolt type junction box cited above, as shown in FIG. 2, the fixing bolt 60 and the fixing nut 70 are disposed in the central portion of the junction box. Thus, a large space is generated in the central portion. This restricts the space in which the connectors can be accommodated.
Second, the one-bolt type junction box cited above has a problem in that three wire harnesses applied to up-to-date motor vehicles cannot be connected to the junction box.
In the up-to-date motor vehicles, the wire harnesses are composed of three wire harnesses for an engine, a body and a front part. However, the one-bolt type junction box cited above has a structure capable of accommodating only two connectors. Therefore, in order to connect three wire harnesses, it is necessary to increase the size of the junction box or to install an additional junction box.